> I believe that this is a result of poor manufacture and that the two > polarizable sheets which form the screen have minimally separated and > are actually leaking a small amount of voltage which causes heat which > causes more separation which causes more leakage, etc. I'm not certain > about the film separation, but I'm pretty sure about the voltage leak > (where ever it comes from) because the polarizable pixels are both > turned "on" which is what causes the darkening.
This is a possibility. My theory (which has been alluded to recently) was that atmospheric pollutants leach into the screen corners (and eventually edges) and essentially cause doping, which facilitates ion transfer and causes a charge to build up. The only cure I've found is time spent with the display unpowered so the charge can dissipate, but physically working the panel as you describe could probably speed up the process. The effect is related to the memory effect that's observed when a static image is left on the screen for a while (which began this latest discussion). That effect is completely normal btw, and always goes away with time when the image is removed (fastest when the screen is off). The difference at the screen corners is that the onset is much faster, and the pixels always become darker regardless of what's displayed - thus I suspect doping. One thing I don't like about your theory is that it should cause accelerating damage, which hasn't been my observation (fortunately). > Out of the 4 PB500 series active matrix grey scale screens that I have > seen so far, 3 exhibit this problem. They were all made by (I think) > Holiden (I know the name starts with an H). The one that is good was > made by Toshiba (and it has 10 dead pixels). I have not seen this > problem in the 3 passive matrix grey scale screens I have or in the two > active matrix color screens that I have. I've never seen it on a colour screen nor a passive screen either, so you may be correct that it's a manufacturing defect (not that these machines were ever designed to last this long). I do observe that all Duo colour displays darken with age and use, but I think this is the backlight wearing out (plus modifed expectations as newer models get brighter and brighter screens). That was also mentioned in the initial query about a darkening 280c. Entirely different phenomenon from the screen corners, of course. -- Marc Sira | [EMAIL PROTECTED] If you can't play with words, what good are they? ---------- Duo/2400 List, The friendliest place on the Net! A listserv for users and fans of Mac subportables. FAQ at <http://www.themacintoshguy.com/lists/DuoListFAQ.shtml> Be sure to visit Mac2400! <http://www.sineware.com/mac2400> To unsubscribe, E-mail to: <[EMAIL PROTECTED]> To switch to the DIGEST mode, E-mail to <[EMAIL PROTECTED]> Need help from a real person? Try. <[EMAIL PROTECTED]> ---------- Dr. Bott | 10/100 Ethernet for your 2400 is finally here! MPC-100 | <http://www.drbott.com/prod/mpc100.html> RoadTools $30 PodiumPad available at Apple retail stores, $20 Traveler CoolPad at Staples. Both in white for iBooks at <http://roadtools.com> Midwest Mac Parts ][ <http://www.midwestmac.com> After-market parts for Macs. ][ 888-356-1104 ][ MacResQ Specials: LaCie SCSI CDR From $99! PowerBook 3400/200 Only $879! Norton AntiVirus 6 Only $19! We Stock PARTS! <http://www.macresq.com>